Digital three-dimensional manufacturing, also known as digital additive manufacturing, is a process of making a three-dimensional solid object from a digital model of virtually any shape. Three-dimensional printing is an additive process in which one or more printheads eject successive layers of material on a substrate in different shapes. Three-dimensional printing is distinguishable from traditional object-forming techniques, which mostly rely on the removal of material from a work piece by a subtractive process, such as cutting or drilling.
The production of a three-dimensional object with these printers can require hours or, with some objects, even days. One issue that arises in the production of three-dimensional objects with a three-dimensional printer is the production of colors in the surface of the objects. During printing of an object, one or more inkjets ejecting colored material can deteriorate and stop ejecting drops or eject drops that are smaller than an inkjet should eject. These inkjet deficiencies can result in objects with faded colors or objects with colors having a different hue than expected. Once the color defects in such objects are detected, the printed objects are scrapped, restorative procedures are applied to the printheads to restore inkjet functionality, and the print job is repeated.
Another issue that arises in the formation of objects with three-dimensional object printers occurs when one color object is embedded in a larger object of a different color that enables the embedded object to be seen. Color fidelity may be lost or color non-uniformity may occur at the boundaries of the embedded object where a transition occurs between the two objects. Consequently, a printer that detects inaccurately colored objects or the loss of color uniformity at boundaries between two different colors within an object while printing would enable the performance of compensatory procedures during object printing. These compensatory procedures enable the printer to produce properly colored objects and increase the productivity of the printer.